A measuring or testing device in the form of a signal generator with several functional units, which can be connected to one another in a variable manner is described, for example, in published German Patent Application No. DE 101 24 371 A1.
Conventionally, measuring or testing devices of a given type (for example, signal generators, spectrum analyzers, network channel analyzers etc.) have been characterized by a different performance dependent upon their equipment package, wherein all of the measuring properties are almost always designed to be of a corresponding, relatively high quality or relatively basic quality at the same time. However, in many cases, only one or a few high-quality properties are required for a given application, wherein other properties can be designed to be considerably more basic. Hitherto, the user has been obliged to purchase a measuring or testing device with a high overall performance, even if the high performance of only a few special measuring properties has been exploited. This has been relatively uneconomical for the user.